Regan Smith, shaping up for a World Championships showdown with Australian Kaylee McKeown, clocked a blistering 2min 03.80sec to win the 200m backstroke at the US swimming championships on Wednesday.
Smith, whose previous world record was broken by McKeown in March with a time of 2:03.14, showed again that her move to train with coach Bob Bowman – former mentor of Michael Phelps – was paying off.
"I haven't been 2:03 in four years, and I'm just so happy to be back where I was," a beaming Smith said after posting the fifth-fastest time ever and beating Rhyan White by 1.97sec.
Smith, who also won the 200m butterfly on Tuesday, set up a tantalising test with McKeown at next month's World Championships in Fukuoka, Japan.
Since breaking' Smith's world mark in March, McKeown has gone on to clock an impressive 2:03.70 at the Australian trials this month.
Elsewhere, 16-year-old Claire Weinstein ran down freestyle great Katie Ledecky to win the 200m free.
Weinstein was second at the 150m mark and overhauled Ledecky over the final 50m to win in 1min 55.26 sec –two-hundredths of a second in front of the seven-time Olympic gold medallist.
"It feels amazing," Weinstein beamed after securing her trip to Fukuoka, Japan, next month.
She had made the team for last year's worlds in Budapest with a runner-up finish to Ledecky in the 200m free at trials. She earned a 4x200m free relay gold but was eliminated in the semifinals and she's looking to improve on that this time.
Ledecky had already shown she remains a force to be reckoned with on Tuesday, winning the 800m freestyle in a 8:07.07 - her fastest time since she set the world record of 8:04.79 at the Rio Olympics in 2016.
Ledecky won 200m free gold in Rio but was fifth at the Tokyo Games in 2021 in the event that is at the lower edge of her remarkable freestyle range.
She didn't swim the 200m free at last year's worlds, and if she opts out again that would open the door for third-place finisher Bella Sims in the individual event.
Michael Andrew won the 50m butterfly in 23.11sec with Dare Rose second in 23.20.
Caeleb Dressel, a seven-time Olympic gold medallist and 14-time World Champion who returned to competition last month for the first time since withdrawing from last year's worlds, was third in an encouraging sign for his comeback bid.
In the women's 50m fly, Gretchen Walsh punched her ticket to Japan with an American record of 25.11. Torri Huske was second in 25.33 – both under Huske's previous national record of 25.38.
Lilly King and Ryan Murphy lined up world title defenses. King held off Kate Douglass to win the 200m breaststroke in 2:20.95 while Murphy booked a fifth world championships team berth with a 200m backstroke win in 1:55.03.
University of Texas talent Luke Hobson used a late surge to win the men's 200m free, powering from third at the final turn to win in 1:45.18 ahead of Kieran Smith.